Subsea natural gas hydrates, as a new undersea energy resource have huge reserves. The global subsea gas hydrate reserves are twice as much as the existing natural gas and oil reserves. There are also abundant natural gas hydrates in the South China Sea and the East China Sea, which have broad development prospects. As a large developing country with a shortage of petroleum resources, China has determined a major strategic decision to explore and develop subsea natural gas hydrate resources as an alternative energy source. It is a necessarily technical step and a method to employ a submersible core drilling rig for a pressure coring on natural gas hydrates to determine the shapes of subsea gas hydrate bodies, to understand geological conditions of subsea gas hydrates and to conduct economic and technical evaluations of subsea gas hydrate resources. The subsea natural gas hydrates often appear staggered or mixed with sediments, sand or hard rocks on the sea floor, forming a soft formation represented by softer sediments, a medium-hard formation represented by a harder sediment formation, a sand formation or an incompletely consolidated hydrate formation, and a hard formation represented by a hard sediment formation, a fully consolidated hydrate formation or a hard rock formation. It lacks of technical experience of adopting submersible core drilling rigs using pressure wireline, submersible core drilling rigs using non-pressure wireline and ordinary submersible core drilling rigs using non-pressure to achieve high efficiency and high core recovery rate of subsea gas hydrates at home and abroad. Meanwhile, it is extremely critical to achieve pressure sealing of core samples because that the subsea natural gas hydrates are formed and stored under low temperature and high pressure. Therefore, the submersible core drilling rig using pressure wireline is used to achieve a high-efficiency coring for subsea gas hydrates and to realize pressure sealing at the same time.